Monday, March 18, 2013

This winter, we began removing Ash trees infected with the Emerald Ash Borer (EAB) that were visibly declining or dead in 2012 and deemed hazardous to people or property. So far, 44 of 286 Fraxinus (Ash) species trees have been removed leaving 242. All of the remaining are infected and in various states of decline.

The EAB is a non-native, phloem-feeding insect that aggressively kills both healthy and stressed Ash trees of all ages. The EAB adult, a metallic green beetle, lays eggs in the bark of Ash trees. These eggs hatch into larvae which bore through the bark and into the cambium where they feed, overwinter, and pupate. It is the larval stage which kills the tree once the cambium is girdled by feeding. See the USDA’s “Emerald Ash Borer Program Manual” for more information.

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Emerald Ash Borer S-shaped galleries

Emerald Ash Borer larvae

The EAB was first identified in Villa Park in the summer of 2011 but we did not have conclusive proof on the golf course until February 2012 last year. During the winter from 2011 to 2012, woodpeckers were seen attacking Ash trees and leaving light-colored marks where the bark had been peeled away. These marks are the easiest way to identify EAB infection over the winter. While the woodpeckers may be feeding on native borers that attack stressed trees, if the tree was previously healthy, EAB is strongly indicated. By the time you see woodpecker damage, the borer has already done significant damage during the year. It is best to call a professional arborist as soon as possible to determine a course of action.

Many people ask me whether they should treat their Ash trees with pesticides or remove them. There is no easy answer to that questions. Ash trees can be saved even after infection with the right treatments -- this is true. The important thing to remember is that treatment is forever or, more accurately, for the life of the tree.If you miss treatments or happen to be in the small percentage where the treatment is ineffective, the tree will again be at risk of infection. The other important thing to remember is this: no matter what you do, you still have an Ash tree. Ash trees are not long-lived or structurally strong. They tend to suffer severe storm damage later in life and can be hazardous.

The factors that need to be considered include:

Cost

Location, location, location

Size of the tree

Age of the tree

Condition of the tree

Potential hazards

Environmental impact of pesticide use

Willingness to commit to treatment for decades, or the life of the tree

As you might have guessed from the above, it is my opinion, verified by a lot of calculations, that it is almost always more desirable and cost-effective to remove an Ash tree and replace it with a more disease-resistant, longer-lived, and safer tree. I know many arborists selling treatment will argue with me, but the math is not on the side of treatment in the vast majority of cases. If you have an Ash tree that you consider invaluable to your property and it is in good condition and it isn't too old and it is not likely to become a hazard, then I would consider treatment. If not, cut your losses and plant something else!

The graphs below were created using the Purdue EAB Cost Calculator﻿﻿﻿. As you can see, with Sugar Creek's large Ash population it is not cost effective to try and save all of our Ash trees. These costs are Purdue's estimate and may be higher than we could do the work for, but the relative costs are what counts. With a removal program combined with replacement of the landscape trees over time, the cost of the strategy disappears in 10 years or so. With treatment, it never disappears and the trees will still die some day with age and storm damage.

Below is a picture of Ash storm damage. After almost every wind event, some older Ash trees need to be pruned or removed. This is true for both golf course trees and street trees. Most of the Ash trees at Sugar Creek are older and were in decline before the borer arrived. They were becoming hazardous to the clubhouse and driving range net, so their removal will give us a chance to plant trees more suited to the location.

Typical Ash tree storm damage

Most of the Ash trees at Sugar Creek are located along the fencelines around the driving range and on the 6th hole. Over the next few years, these trees will be removed and replaced with a variety of disease-resistant trees and shrubs. We are beginning replacements for the 44 trees removed this winter this spring behind the 6th green.

2 comments:

It is always sad to see trees being cut down especially ones you have cultivated and grown to be part of your course but that infestation looks pretty nasty and not one to do nothing about. Have they thought about the impact on drainage on the course and what they will do to compensate?

Thanks for your comment. It is sad to see so many trees taken down, especially all at once. The Emerald Ash Borer is amazingly fast and effective at killing trees. By the time you see one tree with signs of infection, you can be sure that almost every Ash tree in the area is infected. One consolation is that many of the trees were near the end of their life and becoming hazardous. We are taking into account the impact that less foliage will have on drainage as well as wildlife habitat. The trees will be replaced with native trees and shrubs that will enhance the local ecosystem.